Role of strontium addition on the phase transition of lanthanum copper oxide from K2NiF4 to perovskite structure

Ho Chieh Yu, Kuan Zong Fung

研究成果: Article同行評審

5 引文 斯高帕斯(Scopus)

摘要

Without Sr addition, the sintered La2O3 and CuO powder mixture in a mole ratio of 1:2 formed K2NiF4-structured La2CuO4 with excess CuO. When 15% of strontium was added, La2CuO4 transformed into the single perovskite La1-xSrxCuO2.5-δ phase with orthorhombic structure. As the strontium addition increased to 20%, the perovskite lattice changed from orthorhombic to tetragonal. These phase transitions may be attributed to the enhanced oxidation of the divalent cupper ions (Cu2+) to trivalent ones (Cu3+) by the strontium addition. Based on the electroneutrality in an ABO3 perovskite lattice, a divalent cation is unstable in the B-site cation sub-lattice when the A-site is occupied by a trivalent cation such as La3+. As strontium was added into the A-site cation sub-lattice, the oxidation of Cu2+ ion into trivalent Cu3+ ion was enhanced. The increase of Cu3+ concentration strengthened the electrostatic bonding (ESB) of copper ions with their neighboring anions. Consequently, the symmetrical tetragonal Sr-doped lanthanum copper oxide was obtained.

原文English
頁(從 - 到)62-68
頁數7
期刊Journal of Alloys and Compounds
440
發行號1-2
DOIs
出版狀態Published - 2007 8月 16

All Science Journal Classification (ASJC) codes

  • 材料力學
  • 機械工業
  • 金屬和合金
  • 材料化學

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